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TROPICAL DEPRESSION TWELVE-E SPECIAL DISCUSSION NUMBER 1
NATIONAL WEATHER SERVICE MIAMI FL
9 AM PDT SUN SEP 05 1999
THE LARGE MONSOON-TYPE DISTURBANCE THAT HAS PERSISTED OFF THE
MEXICAN COAST FOR THE PAST FEW DAYS HAS BECOME BETTER ORGANIZED
ABOUT 50 MILES SOUTHWEST OF MANZANILLO. SATELLITE INTENSITY
ESTIMATES FROM TAFB AND SAB ARE 30 KT...SO ADVISORIES ARE INITIATED
ON TROPICAL DEPRESSION TWELVE-E.
THE INITIAL MOTION IS UNCERTAIN...WITH THE BEST ESTIMATE OF 340/06.
WATER VAPOR IMAGERY INDICATES AN ANTICYCLONE OVER NORTHERN MEXICO
WITH LARGE UPPER LEVEL LOW DEVELOPING WEST OF SOUTHERN CALIFORNIA.
THIS SUGGESTS A NORTHWESTWARD MOTION...WHICH IS SUPPORTED BY THE NHC
HURRICANE GUIDANCE. THE OFFICIAL TRACK FORECAST STARTS WITH A SLOW
NORTH-NORTHWEST MOTION THAT TURNS MORE NORTHWEST IN TIME.
THE DEPRESSION HAS GOOD CONVECTIVE BANDING AND GOOD OUTFLOW...AND
THUS COULD BECOME A TROPICAL STORM THIS AFTERNOON. THE FORECAST
TRACK KEEPS THE SYSTEM OVER WARM WATER...SO GRADUAL STRENGTHENING IS
FORECAST WITH THE CYCLONE REACHING HURRICANE STRENGTH IN ABOUT 48
HOURS.
DUE TO THE EXPECTED STRENGTHENING AND PROXIMITY TO THE MEXICAN
COAST...TROPICAL STORM WARNINGS ARE BEING ISSUED FOR THE AREA
BETWEEN MANZANILLO AND CABO CORRIENTES...AS WELL AS FOR THE ISLAS
MARIAS. THE CYCLONE COULD THREATEN OTHER PARTS OF THE MEXICAN
COAST... INCLUDING BAJA CALIFORNIA...OVER THE NEXT THREE DAYS.
BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 05/1600Z 18.7N 105.2W 30 KTS
12HR VT 06/0000Z 19.7N 105.7W 35 KTS
24HR VT 06/1200Z 20.7N 106.4W 45 KTS
36HR VT 07/0000Z 21.5N 107.3W 55 KTS
48HR VT 07/1200Z 22.5N 108.5W 65 KTS
72HR VT 08/1200Z 23.5N 111.0W 65 KTS
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